But Boeing acknowledged it’s just the first step in a process of “extensive testing and analysis,” including flight tests by two designated 787s.

And leading industry figures, while they expressed confidence in Boeing’s fix, said that even once the FAA clears the planes for service, getting the 50 grounded Dreamliners operational again and resuming the delayed deliveries could take months.

Philip Scruggs, executive vice president for International Lease Finance Corp., the 787’s largest customer with 74 jets on order, said Tuesday that though the lessor’s first Dreamliner was due in April, “it’ll be the summer” before they can get it.

The fix includes a completely redesigned battery.

“There isn’t a date yet,” Scruggs said. “The date will depend on the ability of the battery manufacturer to ramp up production of those batteries.

“It’ll depend on getting the airplanes that need the batteries as replacements — the airplanes that are in service — up in the air first, then getting the airplanes on the production line retrofitted and out the door.”

Scruggs added that he has “100 percent confidence in Boeing’s solution” and praised the manufacturer for keeping him and other near-term customers informed of the latest developments “on a daily basis.”

Scruggs spoke on the sidelines of the International Society of Transport Aircraft Trading airplane finance conference in Orlando, Fla.

Also at the conference, Steven Udvar-Hazy, chief executive of Air Lease Corp and the industry’s leading authority on the airplane market, praised the FAA’s “constructive role” in approving Boeing’s plan, calling it “a good step forward.”

But Udvar-Hazy too indicated that Boeing still has a way to go, including convincing Secretary of Transportation Ray LaHood, who has said he wants to be “1,000 percent sure” the 787 is safe before it’s allowed back in service.

“Boeing will have to do an extensive flight testing program, will have to do validation, and I still don’t know where we are with the Secretary of Transportation and the Japanese civil aviation authorities,” Udvar-Hazy said.

Both LaHood and FAA chief Michael Huerta indicated Tuesday that the testing regime will be stringent.

LaHood said regulators “won’t allow the plane to return to service unless we’re satisfied that the new design ensures the safety of the aircraft and its passengers.”

Boeing’s Dreamliners have been grounded since mid-January after battery failures caused a battery fire in a jet on the ground in Boston and then a smoldering battery on a flight in Japan. The grounding has halted deliveries of new planes as well as flights by the 50 already delivered to customers.

A Boeing team led by Boeing Commercial Airplanes President Ray Conner on Feb. 22 presented the company’s planned fix to Huerta and other FAA officials.

Boeing’s proposed improvements include “a redesign of the internal battery components to minimize initiation of a short circuit within the battery, better insulation of the cells and the addition of a new containment and venting system,” according to the FAA.

The agency said its certification plan requires a series of tests that must be passed before the 787 could return to service, with specific pass/fail criteria and testing methodology. FAA engineers will be present for the testing and will be closely involved in all aspects of the process, the agency said.

The testing regime will meet a strict standard — stricter than that used by Boeing in originally certifying the Dreamliner.

The more stringent standard was devised by the Radio Technical Commission on Aeronautics, an advisory committee that included senior Boeing engineers, which in 2008 recommended a series of tests to ensure that lithium-ion batteries met FAA regulatory requirements.

One key test requires engineers to turn off the overcharge protections in the battery and induce a thermal runaway — an unstoppable, self-reinforcing process of overheating — to prove that the battery’s reinforced box completely contains the resultant explosion.

That test was not performed during the original certification process. By 2008, Boeing’s Dreamliner had already gone down a different test path toward satisfying the FAA.

Conner described the planned fix for the battery as “a comprehensive set of solutions designed to significantly minimize the potential for battery failure while ensuring that no battery event affects the continued safe operation of the airplane.”

In a Boeing statement, Conner outlined “three layers of improvements.”

One involves redesign of the battery “to prevent faults from occurring and to isolate any that do.”

Another involves “enhanced production, operating and testing processes” for the battery. Reports earlier this month said battery supplier GS Yuasa had been advised by outside experts to tighten inspection and reject more batteries from its production line to ensure the highest levels of quality and performance of the battery and its components.

The third level of protection is an improved system for channeling smoke and volatile liquids out of the airplane “in the unlikely event of a battery failure,” said Conner. He said the “enclosure system … will keep any level of battery overheating from affecting the airplane or being noticed by passengers.”

(END OPTIONAL TRIM)

Even if the battery fix proves solid in testing and those jets are allowed back in the air, negative consequences could linger.

For example, the 787 may face restrictions on how far it can fly from the nearest airport.

The plane was certified by the FAA to fly up to three hours from the nearest airport, but Boeing has applied to have that extended to 5.5 hours to accommodate customers that want to fly ultra-long routes over the ocean or the poles.

Industry experts said the FAA may now balk at that extension, until the jet has at least a year of trouble-free service. That would mean airlines flying longer routes and burning more fuel.

“It will change the operator’s view of how they can use the airplane,” said Peter Huijbers, regional head of commercial with aircraft lessor Hong Kong Aviation Capital.

In addition, Huijbers said, lessors may reduce the appraised values of all the planes that have to be retrofitted with the battery fix.

“You’ll have airplanes that are pre-fix and airplanes that are post-fix,” he said.

And then there is compensation.

Boeing contracts don’t include liability for problems after delivery. But to maintain good relations with its customers, Boeing will still have to compensate them.

“Boeing will fix it,” said Nico Buchholz, head of fleet planning at Germany’s Lufthansa. “It will be expensive. They still have to do something with their customers.”